Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/2011
Publication Date: 7/8/2011
Citation: Gibson, D.M., Krasnoff, S., Biazzo, J., Milbrath, L.R. 2011. Phytotoxicity of antofine from invasive swallow-worts. Journal of Chemical Ecology. 37:871-879. Interpretive Summary: Two emerging invasive plant species in the northeastern United States and southeastern Canada are pale swallow-wort and black swallow-wort. Both species have multiple growth and reproductive characteristics that may play an important role in their invasiveness, including the potential to produce compounds that might affect growth of native plant species within the same environment. In this laboratory study, we identified a particular compound in swallow-wort roots, antofine, that might play a role in inhibiting the growth of several native plants. This identification will aid continuing studies to monitor the presence and accumulation of this compound in the soil and to determine whether it plays a role in the invasiveness of these weeds.
Technical Abstract: Pale swallow-wort (Vincetoxicum rossicum) and black swallow-wort (V. nigrum) are two emerging invasive plant species in the northeastern United States and southeastern Canada that have shown rapid population expansion over the past 20 years. Using bioassay-guided fractionation, the known phytochemical phenanthroindolizidine alkaloid -(-) antofine was identified as a potent phytotoxin in roots, leaves, and seeds of both swallow-wort species. In seedling bioassays, -(-) antofine, at micromolar concentrations, resulted in greatly reduced root growth of Asclepias tuberosa, A. syriaca, and Apocynum cannabinum, three related, native plant species typically found in habitats where large stands of swallow-wort are present. In contrast, antofine exhibited moderate activity against lettuce, and it had little effect on germination and root growth of either black or pale swallow-wort. In disk diffusion assays, antifungal activity was observed at 10 micrograms and 100 micrograms, while antibacterial activity was only seen at the higher level. Although both swallow-wort species display multiple growth and reproductive characteristics that may play an important role in their invasiveness, the presence of the highly bioactive phytochemical -(-) antofine in root and seed tissues indicates a potential allelopathic role in swallow-worts’ invasiveness.